Electromagnetic motor



Nov. 4, 1947. l J. B. WHITTED 2,430,151

ELECTROMAGNETIC IOTOR Filed Aug. 12, 1943 4 Sheets-Sheet 1 Nov. 4, 1947. J. B. WHITTED 2,430,151

ELECTROMAGNETIC IOTOR Filed Aug. 12, 1943 4 SheetsqSheet 2 NOV. 4, 1947. w n' 2,430,151

ELECTROMAGQETIC MOTOR Filed Aug. 12, 1943 4 Sheets-Sheet 3 64 wi i Patented Nov. 4, 1947 ELECTROMAGNETIC MOTOR John B. Whitted, Evanston, 111., assignor to Stewart-Warner Corporation, Chicago, 111., a corporation of Virginia Application August 12, 1943, Serial No. 498,382

10 Claims.

an electric fuel pump having new and improved switch mechanism.

Another object of my invention is to provide an electric fuel pump having new and improved meansdor insuring proper making and breaking of the switch contacts and for minimizing wear, burning, or other deterioration of these contacts.

Another object of my invention is to provide an electric fuel pump having new and improved means for smoothing out the flow of fuel discharged by this pump.

Other objects and advantages will become apparent as the description proceeds.

In the drawings;

Fig. 1 is a vertical, sectional view of a fuel pump embodying my invention; 1

Fig. 2 is a generally transverse, cross-sectional view taken on the irregular line 2-2 of Fig. 1;

Fig. 3 is a transverse view taken on the line 3--3 of Fig. 1;

Figs. 4, 5, 6 and '7 are partial, sectional views showing successive stages in the operation of the switch mechanism and associated parts;

Fig. 8 is a view similar to Fig. 1, but showing a different form of my invention; and v Figs. 9 and 10 are partial, sectional views showing successive stages in the operation of the switch mechanism and associated parts.

The embodimentshown in Figs. 1 to '7, inclusive, has a two-part base, consisting of an upper part i0 anda lower part H. The parts In and I! are preferably made of non-magnetic material and may be formed by die casting, moulding, or in any other suitable manner. The lower part I! has an inlet nipple i4 adapted to be threadedly connected to a pipe leading to the main fuel tank at the rear of an automobile or to any other source of fuel supply. This nipple l4 communicates with an inlet chamber I6 which is closed at its lower end by a plate l3 secured to the part I! by a screw 20. A sealing washer 22 is prefer- I dirt or any other impurities from the fuel before this fuel reaches the pumping mechanism and valves associated therewith. This strainer is held against a shoulder 28 by a spring 30 resting on the plate I8. The central portion 32 of the plate l8 may be recessed to space this central portion from the lower end of the stem 34 into which the screw 20 is threaded, so that greater force can be exerted on the sealing washer 22. This recessed portion 32 also forms a convenient trap for impurities separated from the fuel and these impurities can be removed by unscrewing screw 20 and removing plate I8.

After passing through the strainer 26, the fuel flows upwardly through a passage 36 having a valve seat 38 press fitted therein. A disc valve 40 is pressed against this seat by a spring 42 whose upper end surrounds a projection 44 having ports 46 located around the sides thereof and connecting the passage 36 with a pumping chamber 48. The pumping chamber is closed by a diaphragm 50 clamped between the upper and lower parts l0 and II, respectively, of the base.

Fuel is discharged from the pumpingchamber 48 through a port 52 normally closed by a valve 54. This valve is urged against its seat by a spring 56 resting on a spider 58 press fitted into an outlet passage 60. This passage 60 is sealed from inlet chamber i6 by a sheet metalpartition 62 press fitted into the lower end of the passage 60. An outlet'nipple 64 communicates with the discharge passage Bil and is threaded for attachment to a pipe leading to an engine carburetor, burner, or other device for utilizing the fuel.

The lower part I! of the base has an annular groove 86 located immediately beneath an annular groove 68 provided in the upper part In. A loose, annular portion 10 of the flexible diaphragm 50 divides these annular grooves into two annular compartments of varying capacity. The upper of these compartments contains trapped air, whereas the lower of these compartments is connected by bore 12 with the interior of the outlet nipple 64 whereby fuel discharged from the pumping chamber 48 can flow upwardly through bore 12 and into the annular space beneath the portion 10 of the diaphragm. Annular bands of the diaphragm 50 on opposite sides of the portion 10 are tightly clamped between adjacent portions of the upper and lower parts of the base whereby no fluid or air'can escape from the annular grooves 56 and 68, so that these grooves and the portion 10 of the diaphragm form an an nular compression chamber which minimizes the pulsations resulting from operation of the electric fuel pump.

A steel housing indicated generally by reference number 14 is provided with threaded bosses 16 whereby it may be connected to the two portions of the base by means of screws 18. The housing 14 comprises an outer portion 80 and a sleeve or core 82 having its upper end press fitted into the in-turned upper end of the outer portion 80 to form a unitary structure. The extreme upper end of the sleeve 82 is provided with an annular groove 84 forming an air gap between the extreme end of the sleeve and the adjacent portion of the outer member 80. An electrical coil 86 is located in the housing 14 and is secured in place by a washer 88 and C-ring 80, which is secured in a groove suitably located in the sleeve 82.

A diaphragm operating rod 82, formed of steel drill rod or other suitable magnetic material, is reciprocably mounted in the housing 14 and has an oilless bronze bushing 84 press fitted thereon. This bushing slides freely in the bore of the sleeve 82 and guides reciprocating movement of the rod 82 therein. The lower end of the rod 82 is of reduced diameter and threaded into the central boss of a diaphragm plate 86 located beneath the central portion of the diaphragm. The plate 86 serves to clamp a second diaphragm plate 88 against a thrust washer I abutting a shoulder formed by the reduced lower end or the rod. The plates 86 and 88 lie on opposite sides of the central portion of the diaphragm 50 and. serve to control the position of the diaphragm in the pumping chamber.

An annular spring I02, preferably of beryllium copper about /1000 of an inch thick, has its outer edge clamped between the housing 14 and upper part of the base. The inner portion of this spring is divided into eight tapered segments by radial slots I04. A steel armature segment I06 is soldered, welded, or otherwise suitably secured to one side of each of these spring segments. Each of these armature segments has a curved inner end I08 and tapered sides IIO corresponding respectively to the curved inner end of the spring segments and the tapered sides of these segments. The outer end or base II2 of each armature segment is straight and forms a cord of the circle formed by the adjacent wall of the housing 14. A finger H4 is secured to the under side of each spring segment by soldering, welding, or in any other suitable manner, and each finger has an inner end located beneath the thrust washer I00 and adapted to raise this washer, rod 82, and associated parts when electrical coil 86 is energized.

The upper end of the rod 82 is of reduced diameter, as indicated at I I6, thereby forming a shoulder I I8 which supports a button I20 of aluminum or other non-magnetic material. The extreme lower end of the button is preferably of smaller diameter than the main body of the rod 82 and forms a shoulder I2I spaced slightly above this portion of the rod and of appreciably greater diameter. This button forms a support for the lower end of a diaphragm return spring I24. The upper end of this spring rests in a depression I26 formed in a sheet metal c'over I28 attached to the upper end of the housing 14 by studs I30 surrounded by spacing sleeves I32.

A resilient steel switch I34 has its right-hand end clamped between plates I36 and I38Jsecured to the housing 14 by screws I40. The plate I38 is preferably wedge shaped in cross section to give the switch the normal inclination shown in Fig. 1.

4 The fixed end of the switch is grounded to the housing 14. The switch I34 is provided with an opening I42 through which the rod 82 freely passes. This opening, however, is of smaller diameter than the shoulder I2I of the button I20. That portion I43 of the switch between the opening I42 and the point of attachment to the housing 14 is provided with a longitudinal slot I44 which increases the flexibility of this portion of the switch. That portion I46 of the switch immediately to the left of the center of the opening I42 is made wider than the remaining parts of the switch and constitutes an armature portion which is more strongly attracted by the adjacent end of the housing "I4 than are other portions of the switch. The extreme left-hand end of the switch is oiTset upwardly and is divided into two fingers I48, each of which carries a movable contact I50.

The movable contacts I50 are adapted to engage a pair of stationary contacts I52 carried by a metal switch plate I54 secured to the housing 14 by screws I56. The switch plate I54 is insulated from the housing 14 and screws I56 by an insulating strip I58 and insulating washers I60. One end 86A of the coil 86 is soldered or otherwise secured to the switch plate I54 and this switch plate is grounded through a high resistance I62 having one end soldered to the switch plate I54, as indicated at I64, and the other end soldered to the upper end of the housing I64, as indicated at I66. The other end 86B of the coil 86 is soldered to a terminal plate I68 secured to the housing 14 by a screw I10 and insulated from this housing in any suitable manner.

An electrical conductor I12 connects terminal plate I68 with the positive terminal of a battery I14, or other suitable source of electricity, the other terminal of the battery being grounded as indicated at I16. A switch I18 is preferably interposed between the battery and terminal plate I68. Where my fuel pump is applied to an automobile, this switch I18 would ordinarily be the ignition switch of the automobile electrical system.

When my fuel pump is first assembled, the spring I24 holds the central portion of the dia- -phragm in depressed position with the movable contacts I50 in engagement with the fixed contacts I52. As soon as the switch I18 is closed, the coil 86 is energized and exerts an upward pull on the armature segments I04 and fingers II4. These fingers thereupon exert an upward thrust on the washer I00 and operating rod 92 to raise the central portion of the diaphragm against the resistance of the spring I24. As the armature segments and fingers move upwardly, the sprin I02 flexes along lines connecting the closed ends of the slots I04 and lying immediately adjacent the lower edges of the straight bases II2 of the armature segments I06, so that these lines of flexation constitute the pivots about which the armature segments and fingers move. This initial energization of the electrical coil 86 magnetizes the operating rod 82, which thereupon becomes, and thereafter remains, a permanent magnet.

As the central portion of the diaphragm and the operating rod 82 move upwardly, the switch I34 is held in closed position by the magnetic pull between this switch and the adjacent end of the housin 14. This magnetic pull acts most strongly on the armature portion I46 of the switch and is increased by the presence of the annular groove 84 in the upper end of the housing 14. This causes the slotted portion I43 of the switch I34 to bow upwardly, as clearly shown in Fig. 8, and this upward bulge of the switch is increased somewhat when the bushing 54 first engages the lower side of the switch.

Continued upward movement of the rod 32 and bushing 54 causes the latter to force the armature portion I45 of the spring away from the adjacent end of the housing and to separate the movable contacts I50 from the fixed contacts I52, thereby breaking the circuit to the electrical coil '85. The stress created by the curvature of the slotted portion I43 of the spring just prior to this break causes the contacts I50 to move away from the fixed contacts I52 with a whippin action which materially reduces sparking at these contacts and greatly contributes to the long and trouble-free operation of my invention. The switch I34 immediately assumes the position shown in Fig. 7, with the movable and fixed contacts widely separated. Arcing at the contacts is further reduced by the presence of the resistance I52 which provides a high resistance ground connection for the fixed contacts.

After the circuit of the coil 80 has been broken, upward movement of the rod 82 and central portion of the diaphragm 50 stops and spring I24 exerts a force tending to return these parts to the position of Fig. 4, and to discharge fuel from the pumping chamber 48 into which the fuel was drawn by the preceding upward movement of the diaphragm. After the diaphragm has moved down an appreciable distance, the shoulder I2I of the button I20 engages the switch I34 and moves the free end of this switch downwardly. Fig. 5 shows the position of the parts when the movable and fixed contacts first engage.

The initial engagement of these contacts creates a flow of current in the coil 85 and the effect of this initial flow is to create a condition tending to separate the contacts I50 and I52. It is, therefore, of great importance to provide special means to maintain these contacts in closed position and to prevent the chattering of the contacts which would occur if such special means were' not provided. In my invention the magnetic pull exerted by the shoulder N5 of the magnetic operating rod 32 on the switch I34 suffices to hold the contacts in firm engagement until continued downward movement of the operating rod and button I20 causes the shoulder I2I of the latter to press these contacts together more firmly.

This downward movement of the rod 32 and central portion of the diaphragm continues until the magnetic force built up by the energization of the coil 85 is sufficient to overcome the inertia of the parts and the force exerted by the spring I24, whereupon the movement is reversed. The magnetization of the housing I4 by the coil 85 creates a strong pull between the armature portion I45 of the switch I34 and the adjacent end of the core 32 and this force is sufficient to maintain the switch contacts in firm engagement even after the shoulder I2I is moved upwardly away from the switch I34, as shown in Fig. 6. In fact, this magnetic pull between the switch and housing becomes so strong that a very appreciable force must be exerted against the switch by the bushing 34 before the switch contacts can be separated.

The rate of descent of the central portion of the diaphragm 50 and, therefore, the speed and frequency of operation of the pump, are determined by the rate at which fuel is consumed by the engine to which the fuel pump is connected.

The discharge nipple 54 is in communication by way of passage 12 with the annular diaphragm portion I0 located in the annular chamber formed by the grooves 55 and 58. The discharge stroke of the central portion of the diaphragm causes the annular portion I0 of this diaphragm to compress air in that portion of the annular chamber thereabove, so that during the succeeding upward or intake stroke of the central portion of the diaphragm, this annular portion of the diaphragm is capable of continuing to supply fuel to the carburetor under the force exerted by the air compressed in the upper portion of the annular chamber. This annular chamber, therefore, serves the dual function of prolonging the discharge stroke of the pump and of smoothing out this fiow.

The modification of Figs. 8, 9, and 10, is essentially the same as the embodiment disclosed in Figs. 1 to 7, inclusive. In the second embodiment of my invention, however, diaphragm operating rod 200 is formed of brass or other suitable non-magnetic material and reciprocates in a stationary steel sleeve 202 located in a fixed Bakelite sleeve 204, press fitted into the bore of the central portion or core 82 of the housing I4, The upper end of the rod 200 isof reduced diameter to receive the aluminum button I20, as in the previous embodiment, and this end of the rod has an intermediate reduction 206 providing a second shoulder 208 shown in Fig, 8 as supporting a ferrous washer 2I0. The intermediate portion 205 of the operating rod projects through the opening I42 in the switch I34.

In the position of the parts shown in Fig. 8, the switch contacts are separated and the washer 2 I0 is in engagement with the switch I34 or may be located immediately therebeneath. As the operating rod 200 and central portion of the diaphragm descend, the button I20 engages the upper side of the switch I34 and moves the free end of this switch downwardly until the movable contacts I50 engage the fixed contacts I52. At the time this occurs, the washer 2! is resting upon the upper end of the steel sleeve 202, as shown in Fig. 10, This sleeve constitutes a permanent magnet and the force exerted by this magnet is transmitted through the ferrous washer 2I0 to that portion of the switch I34 which is spaced a short distance above this washer, so that the magnetic force of the permanent magnet 202 offsets the separating magnetic action between the switch and the coil housing which is created immediately after the initial closing of the contacts.

The energization of the electrical coil 86 reverses the direction of movement of the operating rod 200' and Fig. 9 shows an intermediate position of the parts during their upward stroke.

In this figure, the switch contacts are maintained closed by the magnetic attraction of the upperend f the core 82 for the adjacent portion of the switch I34. Further upward movement of the operating rod 200 causes the shoulder 208 to engage and lift the washer 2 I 0. Very shortly thereafter this washer engages the switch I34 to separate the contacts. I34 and the movable contacts carried thereby fly upwardly under the released resilient force of the curved switch and immediately assume the position shown in Fig. 8, so that arcing of the contacts is avoided.

In normal operation, the downward movement of the operating rod and associated parts is reversed when these parts assume-approximately The free end of the switch the position shown in Fla. 10. It is desirable to terminate the downward movement oi the operating rod before the switch I engages the washer Illl so that the pounding noise which would result irom such engagement is liminated. when the ignition switch is turned 01!, there is no ob- Jection to having the parts come to rest with theswitch I 34 engaging the washer 2N.

From the foregoing description taken in connection with the accompanying drawings, it will be apparent that in both forms of my invention I have provided nonpositive means for holding the movable and fixed switch contacts in engagement immediately after the initial engagement of these contacts and while the armature quivers from the initial surge of current. The coil 86 is thereby allowed to take its full current and one enect of this current is to increase the force of engagement between the fixed and movable switch contacts. In other words, the magnetic attraction of the permanent magnet for the switch I34 offsets any separating force which may result from initial closing of the contacts and prevents the contacts from reopening and chattering in a manner which would occur if no permanent mognet or equivalent force were present.

While I have illustrated and described in detail only two embodiments of my invention, my invention is susceptible to many variations and modifications and includes all variations, modifications, and equivalents falling within the scope of the appended claims.

I claim: A

1. Apparatus of the class described, comprising a steel housing, an electromagnet located in said housing, an armature attracted by said magnet, means for movably supporting said armature, a rod moved by said armature in one direction, said rod being of steel, a spring for moving said rod in the opposite direction, a resilient steel switch member carrying a movable contact, and a second switch member having a fixed contact, said resilient member being moved to open and closed positions with movement of said rod, said rod constituting a permanent magnet for holding said resilient member in switch closing position immediately...after initial closing of said contacts.

2. In apparatus of the class described, the

combination of a magnetic housing, an electromagnet mounted in said housing, an armature movable toward and from said magnet, a rod moved in one direction by said armature, a spring for moving said rod in the opposite direction, a switch mounted on said housing, said switch having movable and fixed contacts, said movable contact being mounted on the free end of a resilient switch member, said member being biased toward open position, and means associated with said rod for opening and closing said switch, said resilient member being magnetically attracted by said housing to hold said contacts in closed position, the free end of said resilient member being more strongly attracted by said housing than other portions of said member.

3. Apparatus of the class described, comprising a steel housing having a central opening therethrough, an electromagnet mounted in said housing and surrounding said opening, a rod located in said opening, said rod being of magnetic material, a collar of nonmagnetic material affixed to said rod and guiding reciprocation of said rod in said housing, a movable armature adapted to be attracted by said electromagnet, means carried by said armature for moving said strongly attracted by the magnetic force of said housing and a second portion of lesser crosssection adapted to flex when said switch member is in closed position.

4. Apparatus of the class described, comprising an annular electromagnetic coil, a housing supporting said coil, an annular spring attached to said housing, said spring having radial slots dividing the inner portion of said spring into a plurality of tapered segments, armature segments attached to said spring segments, said armature segments having tapered sides corresponding to the tapered sides of said spring segments and bases having straight edges determining the line of flexation for said spring segments, a reciprocable rod, means attached to said spring segments and armature segments for moving said rod in one direction, other means for moving said rod in the opposite direction a switch controlling the supply of current to said electromagnetic coil, and means associated with said reciprocable rod for opening and closing said switch.

5. Apparatus of the class described, comprising a housing having an annular wall, an electromagnet mounted in said housing, a plurality of armature segments adapted to be attracted by said magnet, spring means for supporting said armature segments, said spring means comprising an arcuate base and tapered segments formed by radial slots, said spring segments being attached to said armature segments constituting a pivotal mounting therefor, said spring segments urging said armature segments away from said electromagnet, a rod reciprocable relative to said housing, fingers carried by said spring segments for moving said rod in one direction a switch controlling the supply of current to said electromagnetic coil, and means associated with said reciprocable rod for opening and closing said switch.

6. Apparatus of the class described, comprising a magnetic housing, an electromagnet located in said housing, an armature attracted by said magnet, means for movably supporting said armature, a rod moved by said armature in one direction, said rod being of magnetic material, a spring for moving said rod in the opposite direction, a resilient steel switch member carrying a movable contact, and a second switch member having a fixed contact, said resilient member being moved to open and closed positions with movement of said operating rod, said rod constituting a permanent magnet for holding said resilient member in switch closing position immediately after initial closing of said contacts.

7. In apparatus of the class described, the combination of a magnetic housing, an electromagnet mounted in said housing, a plurality of armatures movable toward and from said magnet, a rod moved in one direction by said armatures, a spring for moving said rod in the opposite direction, a switch mounted on said housing, said ing and surrounding said opening, a rod located in said opening, said rod being of magnetic material, a collar of nonmagnetic material aflixed to said rod and guiding reciprocation of said rod in said housing, a movable armature adapted to be attracted by said electromagnet, a spring pivotally supporting said armature, means carried by said armature for moving said rod in one direction, a second spring for returning said rod. a fixed switch member attached to one end of said housing, a resilient switch member having one end attached to said housing and a second end adapted to move into and out of engagement with said fixed switch member, a nonmagnetic button carried by said rod for moving said resilient switch member to closed position, said collar being adapted to move said resilient switch member to open position, said resilient switch member being of magnetic material, and said resilient switch member having a first part strongly attracted by the magnetic force of said housing and a second portion of lesser cross section adapted to flex when said switch member is in closed position.

9. Apparatus of the class described, comprising an annular electromagnetic coil, a magnetic housing supporting said coil, an arcuate spring attached to said housing, said spring having radial slots dividing the inner portion of said spring into a plurality of tapered segments, armature segments attached to said spring segments,

said armature segments having tapered sides corresponding to the tapered sides of said spring segments and bases having straight edges determining the line of flexation for said spring segments, a reciprocable rod, means attached to said spring segments and armature segments for moving said rod in one direction, other means for moving said rod in the opposite direction, and switch means for said coil, said switch means including a flexible magnetic member attracted by said housing, said housing having a groove to increase the attraction between said housing and flexible member.

10. Apparatus of the class described, comprising a housing having an annular wall, an electromagnet mounted in said housing, a plurality of armature segments adapted to be attracted by said magnet, spring means for supporting said armature segments, said spring means comprising an arcuate base and tapered segments formed by radial slots, said spring segments being attached to said armature segments and constituting a pivotal mounting therefor, said spring segments urging said armature segments away from said electromagnet, a rod reciprocable relative to said housing, fingers carried by said spring segments for moving said rod in one direction, and means for moving said rod in the opposite direction.

JOHN B. WHIT'IED.

REFERENCES CITED The following references are of record in the file of this patent:

' UNITED STATES PATENTS 

